Atraumatic Gastrointestinal Anchor

ABSTRACT

The present invention relates to methods and articles for anchoring within a natural bodily lumen. An anchor is adapted to provide differing radially-outward forces along its length, a securing force and a transitional force. Production of these forces can be controlled by varying a physical property of the anchor, such as its stiffness, thickness, or shape. For example, the stiffness of an elongated anchor can be varied from a relatively soft value at its proximal and distal ends to a relatively stiff value at its center by varying the diameter of wire forming the anchor, thereby tailoring it to an intended application. Such force tailoring can be combined with external barbs and used to reliably anchor other instruments, such as feeding tubes and intestinal sleeves.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/229,352, filed on Sep. 16, 2005, which claims the benefit of U.S.Provisional Application No. 60/611,038, filed on Sep. 17, 2004.

The entire teachings of the above applications are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

Anchors are used in the treatment of patients to secure devices at adesired location within a natural bodily lumen. For example, anchors canbe used to secure tubes within the digestive tract, such as intestinalsleeves. For example intestinal sleeves anchored within thegastrointestinal tract are described in U.S. application Ser. No.10/339,786 filed on Jan. 9, 2003, claiming priority to U.S. ProvisionalApplication No. 60/430,321 filed on Dec. 2, 2002; 10/858,852 filed onJun. 16, 2004, claiming priority to U.S. Provisional Application Nos.60/528,084 filed on Dec. 9, 2003 and 60/544,527 filed on Dec. 14, 2004,incorporated herein by reference in their entirety.

SUMMARY OF THE INVENTION

This invention is generally related to articles and methods foranchoring within a natural bodily lumen, and particularly to articlesand methods for anchoring atraumatically.

Unfortunately, stiff anchors can traumatize surrounding tissue. This isparticularly true in biological applications in which the anchoroperates against softer bodily tissues. A stiff anchor may be usedwithin a bodily lumen, such as the intestine to prevent a medical device(e.g., a sleeve) from migrating therein. In some applications, theanchor includes barbs adapted to pierce a portion of the lumen. For thebarbs to be effective, at least some of them must engage the tissue atall times. To accomplish this continued engagement, anchors provide asufficient securing force adapted to maintain the barbs within thetissue. As this securing force can be substantial, tissue damage at theproximal and distal ends of the anchor are likely to occur.

To anchor within a lumen, anchors generally apply at least some outwardforce directed toward the inner walls of the lumen. Depending upon theapplication, the anchoring force can vary from a minimal force (e.g., tohold hooks in position) to a more substantial force (e.g., forming aninterference fit). In biological applications the inner walls of a lumentypically contain tissue that is soft and particularly vulnerable toirritation. Thus, in these applications a greater force increases therisk that the anchor will lead to trauma by way of irritation or eventissue damage.

Such irritation and tissue damage are particular concerns for anchorsadapted for use within the intestine. Unfortunately, the high mobilityof the intestine and the nature of the forces acting on material withinthe intestine (i.e., peristalsis) complicate anchoring there. Thus, amore substantial force is typically required to secure an intestinalanchor in place.

The present invention relates to an intraluminal anchor adapted forimplanting within a natural bodily lumen. The intraluminal anchorincludes an elongated anchor having a longitudinal axis adapted foralignment with the natural bodily lumen. The elongated anchor includes aprimary anchoring region adapted to expand against the lumen. The anchoralso includes secondary anchoring regions disposed along either side ofthe primary anchoring region. The secondary anchoring regions are alsoadapted to expand against the lumen with the primary anchoring regionexpanding to a greater extent than the outer ends of the secondaryanchoring regions.

The intraluminal anchor also includes an elongated anchoring memberthat, when implanted, provides at least two different radial forces atrespective positions along its length. These different radial forces actdifferently upon respective portions of the natural bodily lumen whenthe device is implanted therein. Namely, at least one of the radialforces is primarily a securing force adapted to anchor within thenatural bodily lumen. The other radial force is a transitional forceadapted to mitigate damage to the natural bodily lumen. Further, whenimplanted, the intraluminal anchor defines an interior lumen allowingfor continued functioning of the natural bodily lumen.

The elongated anchoring member can include plural anchoring elementseach providing a respective radial force, at least one of the elementsproviding a different radial force from the others. By positioning eachof the plural anchoring elements at a respective position along thelength of the intraluminal anchor, the respective radial forces,including the different radial force, are disposed at different lengthsalong the natural bodily lumen.

The different radial force can be provided by forming one or more of theanchoring elements from a different material than the other anchoringelements. Preferably, the different materials provide differentcompliance values that produce different radial forces when implanted.Alternatively, or in addition, the different anchoring elements can beformed from the same material but in a different configuration, such asits shape or thickness.

At least some of the anchoring elements can be coupled to each other.For example, in some embodiments at least one joining member is coupledbetween adjacent anchoring elements, the joining member coupling two ormore anchoring elements together.

In some embodiments having plural anchoring elements, at least one ofthe anchoring elements can be formed from an elongated wire. Theelongated wire can be formed in any suitable shape, such as a helix oran oscillating (i.e., wave-shaped) pattern. The wave-shaped patterndistributes the respective radial force over the length of the anchoringelement while also improving performance of the anchoring element'srespective radial expansion and contraction.

To further enhance its anchoring performance, the intraluminal anchorcan include at least one external barb adapted to penetrate tissue ofthe natural bodily lumen. The external barb is located at apredetermined position along the length of the intraluminal anchor, thecorresponding radial force acting to press the barb into the tissue. Forexample, in a multi-anchoring element embodiment, the at least oneexternal barb can be coupled to one of the anchoring elements. The forceof the coupled anchoring element then acts to hold the barb within thetissue.

In some embodiments, the external barb can be a bi-directional barb.Bi-directional barbs are particularly well suited for applications inwhich the intraluminal anchor is subjected to external forces acting ineither direction along the natural bodily lumen. Generally, thebi-directional barb includes a first barb segment adapted to opposeproximal movement and a second barb segment adapted to oppose distalmovement. Such barbs are well suited to gastrointestinal applications inwhich the device is subjected to the substantial axial forces ofperistalsis.

Preferably, the anchor is radially collapsible for endoscopic insertion.The intraluminal anchor can also include a drawstring to facilitaterepositioning and/or removal. The drawstring, for example, can beprovided at a proximal end of the device and be adapted for engagementby a removal device, such as a hook. The drawstring, when engaged, canbe pushed or pulled by the removal device, in opposition to thestationary intraluminal anchor, to at least partially collapse at leastpart of the intraluminal anchor. With a reduced diameter, the device canbe removed through, or repositioned within, the natural bodily lumen. Insome embodiments, at least a portion of the device is drawn into aretrieval hood, sheath, or overtube prior to removal.

In some embodiments, the intraluminal anchor is coupled to an elongatedtube at a proximal end of the tube, the tube being adapted to extenddistally within the natural bodily lumen. The elongated anchoringelement can be coupled to the elongated tube in any of a number ofdifferent ways. For example, the anchoring element can be mechanicallyfastened using sutures, staples, or the like. Alternatively or inaddition, the anchoring element can be bonded to the tube, using achemical adhesive and/or heat welding. In some embodiments the tube isthin-walled, and flexible. For example, the tube can be formed as asleeve having extremely thin and floppy walls, the sleeve tending tocollapse upon itself. The anchoring element can secured between at leasttwo overlapping layers of the sleeve. The overlapping layers can then beattached to each other using any available fastening technique includingbonding together at least a portion of the overlapping layers of thesleeve.

In other embodiments, the elongated anchoring element can be formed froma homogeneous hollow tube. The thickness of the tube can be altered(i.e., tapered) along the length of the tube, such that differentportions of the tube provide different spring forces. When implantedwithin a naturally bodily lumen, the tapered tube provides differentforces along its length and therefore different forces along the bodilylumen according to the thickness of the tube. In some embodiments, thetapered tube can be further modified using known techniques (e.g., lasercutting) to promote radial expansion and contraction of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1A is a schematic diagram illustrating a prior art intraluminalanchor implanted within a natural bodily lumen.

FIG. 1B is a schematic diagram illustrating an embodiment of anintraluminal anchor according to the principles of the inventionimplanted within a natural bodily lumen.

FIG. 2 is a schematic diagram illustrating an embodiment of anintraluminal anchor.

FIG. 3 is a schematic diagram illustrating an embodiment of a bendable,intraluminal anchor.

FIG. 4A is a schematic diagram illustrating an alternative embodiment ofthe intraluminal anchor shown in FIG. 1.

FIG. 4B is an exemplary radial-force profile for the intraluminal anchorof FIG. 4A.

FIGS. 5A and 5B are schematic diagrams illustrating alternativeembodiments of the intraluminal anchor shown in FIG. 2 havingcross-linking members.

FIG. 6 is a schematic diagram illustrating an alternative embodiment ofthe intraluminal anchor shown in FIG. 4A having multiple coupled waveelements.

FIG. 7 is a schematic diagram illustrating a cross-sectional view of anembodiment of the intraluminal anchor device shown in FIG. 2 attached toa tube and implanted within a natural bodily lumen.

FIG. 8 is a schematic diagram illustrating a cross-sectional view of theintraluminal anchor device shown in FIG. 7 implanted within the proximalduodenum.

FIG. 9A is a schematic diagram illustrating an embodiment of a shapedtube. FIG. 9B is a schematic diagram illustrating an embodiment of anintraluminal anchor formed from the shaped tube shown in FIG. 9A.

FIG. 9C is an exemplary radial-force profile for the intraluminal anchorof FIG. 9B.

DETAILED DESCRIPTION OF THE INVENTION

A description of preferred embodiments of the invention follows.

An anchor is adapted for anchoring within a natural bodily lumen whileallowing continued functionality of the lumen and providing minimaltrauma to the surrounding anatomy. Such an anchor provides a securingforce acting upon the surrounding anatomy to hold the anchor fast, evenin the presence of anticipated biological forces. For example, thesecuring force would hold a gastrointestinal anchor in position even inthe presence of peristalsis. Anchoring against such forces, however, mayrequire substantial securing force that could otherwise damage thesurrounding tissue.

A cross-section of a natural bodily lumen 20 including an anchor 10 b′is illustrated in FIG. 1A. Generally, the lumen defines a naturaldiameter, D₁, that may vary over time. The anchor provides aradially-outward securing force directed against the luminal walls.Depending upon the structure of the anchor 10 b′ and the compliance ofthe luminal walls, the anchor 10 b′ when implanted can increase theintraluminal diameter (i.e., D₂) as shown. The sharp transition from theanchored region to the unsupported adjacent region applies a strain tothe tissue, particularly at the ends of the anchor 25. As shown, tissuestretching can occur over a first distance Δ₁. Such a strain can lead toirritation of the tissue or even damage over time.

To offset the possibility of damage due to the securing force, theanchor also provides a transitional force that is different from thesecuring force and acts upon an adjacent region of the surroundinganatomy. As shown in FIG. 1B, an anchor 10 b″ providing a securing forceis surrounded on either side by another anchoring element 10 a−, 10 c″providing a lesser, transitional force. The transitional force allowsfor a more gradual decrease in anchoring force from a central regionalong the length of the anchor and thus less trauma. Thus, thetransition from an expanded diameter D₂ to the natural luminal diameterD₁ occurs over a second distance Δ₂, that is greater than first distanceΔ₁. By transitioning from unsupported tissue to anchored tissue using asofter anchoring element, the strain to the tissue is reduced, therebyreducing the likelihood of tissue irrigation and damage.

By applying different forces at different lengths along the naturalbodily lumen, the securing force can be applied, or focused whereneeded, while the transitional force can distribute the pressure loadingto the surrounding anatomy. In particular, the transitional force is alesser force than the securing force, providing a gradual transitionfrom the luminal region subjected to the securing force, to adjacent,unsupported luminal regions. Preferably, the anchor can be used incombination with another instrument, such as a feeding tube or agastrointestinal sleeve, to secure the instrument at a predeterminedlocation within the bodily lumen.

FIG. 2 schematically illustrates an exemplary embodiment of anintraluminal anchor 100. The anchor 100 has an overall axial-length ‘L’measured length-wise with respect to the lumen and defines an interiorchannel 115 configured to allow continued operation of the lumen whenimplanted therein. For example, the anchor 100 can have a generallycylindrical shape, having a length ‘L’, a diameter ‘D’, and defining aninterior channel 115. When implanted, the anchor provides aradially-outward spring force directed against the adjacent walls of thenatural bodily lumen (i.e., the anchor includes an annular, radialspring providing a force corresponding to a displacement of the springalong its radius). The radial force includes a securing force,sufficient to secure the anchor 100 in place under anticipated bodilyforces. In particular, the outward radial force is varied along thelength of the anchor to provide a transitional force, reducing thelikelihood of damage to surrounding tissue. When implanted within anatural bodily lumen, the anchor provides a transition along the lumenfrom soft tissue, to a low compliance region (i.e., transitional force),to a higher compliance region (i.e., securing force), again to a lowcompliance region, and ultimately back to unsupported, soft tissue.

Generally, the anchor includes a spring providing the desired securingforce. The force produced by the spring is defined by an associatedspring rate relating to its compliance or stiffness. The spring rate canbe determined by one or more anchor features including its type ofmaterial, material thickness, dimensions, and shape. As a radial spring,a greater force results from a greater radial displacement. Forintraluminal applications, such a radial spring preferably has a relaxeddiameter (i.e., no load diameter) that is greater than the largestanticipated intraluminal diameter. Thus, the implanted anchor is alwayssubjected to a compressive force causing radial compression and leadingto an opposing securing force. Compliant anchors are described in U.S.application Ser. No. 11/147,992 filed on Jun. 8, 2005, incorporatedherein by reference in its entirety.

In many applications the anchor remains sufficiently compliant, whenimplanted, to conform to the walls of the lumen over a full range ofmotion. For example, an anchor implanted within the proximal duodenum ofan adult human may experience intraluminal diameter variations fromabout 25-millimeters or less, to greater than 50-millimeters.

As suggested by FIG. 2, the anchor 100 can provide a varied force byusing plural anchoring elements. For example, the anchor 100 can includethree or more different anchoring elements 110 a, 110 b and 110 c(generally 110), as shown. Each of the anchoring elements 110 a, 110 band 110 c can be annular, as shown, and occupy a respective axialsub-length ‘l₁,’ ‘l₂,’ and ‘l₃.’ Further, each of the anchoring elements110 can be separated from its neighboring anchoring element by arespective distance ‘s₁,’ ‘s₂.’ In some embodiments, the one or more ofthe distances can be negative, suggesting that the elements overlap. Theoverall length of the anchor 100 is determined as the sum of thesub-lengths of the anchoring elements and any distances providedtherebetween. Each of the annular anchoring elements 110 can be sizedand shaped to conform to the walls of the surrounding lumen with itsopening collinearly aligned with a luminal axis.

In some embodiments, the anchoring elements 110 are coupled togetherusing a respective cross-linking, or joining member 120 a, 120 b(generally 120), as shown. The joining member 120 can be a rigid memberor strut, such as a wire or rod. Use of rigid struts can reduce orsubstantially eliminate axial compression of the device. Alternativelyor in addition, the joining member 120 can be flexible, such as a wire,tape, or thread (e.g., a suture). Such flexible members can permit axialcompression but not expansion, so the length can be less than or equalto a maximum length. If axial compression and expansion is desired, thejoining members 120 can include elastic elements. Such flexibility canbe beneficial to both patient comfort and anchoring effectiveness. Insome embodiments, the joining members 120 are formed integrally to theanchoring elements 110 themselves.

An embodiment of a flexible elongated anchor 200 is illustrated in FIG.3. The elongated anchor 200 can include more than one anchoring element210 a, 210 b, 210 c, each capable of independent movement with respectto the other elements. The anchor 200 may include joining members 220 a,220 b, but they are selected and positioned to allow a desiredflexibility. For example, rigid joining members can be aligned along oneside of the anchor 200, allowing the anchor to bend towards that side.

An alternative embodiment of an intraluminal anchor 300 is illustratedin FIG. 4A. The anchor 300 includes multiple anchoring elements 310 a,310 b, 310 c in a collinear arrangement with adjacent elements 310abutting. A corresponding force-versus-distance graph for the anchor 300is illustrated in FIG. 4B. In particular, the graph illustrates thedifferent radially-outward forces provided by each of the anchoringelements 310 (FIG. 4A) versus its respective distance as measured alonga central axis of the anchor 300. As shown for the exemplary embodimentof FIG. 4A, the greater radial force is provided by the central element310 b, having a representative force of F₂. The corresponding force canbe substantially constant across the axial length subtended by thesecond anchoring element 310 b (i.e., from L/3 to 2L/3, assuming allthree elements are of equal length L/3). Similarly, forces F₁ and F₃provided by the adjacent first and third anchoring elements 310 a, 310 care lesser forces, as shown in the graph (e.g., at region 320). Thegreater force F₂ corresponds to a securing force to hold the anchor inplace when implanted; whereas, the lesser forces F₁ and F₃ correspond totransitional forces lessening the likelihood of damage to surroundingtissue.

In some embodiments, however, the structure of the anchoring elements310 allows the elements to provide different forces along theirrespective sub-lengths. As the anchoring elements 310 are radialsprings, they have an associated spring constant. The radial forceprovided by the anchoring element 310 is thus a result of the springconstant and the amount of radial compression. Anchoring elementconfigurations that allow for varied compression along the anchorsub-length will lead to a corresponding varied radial force. Forexample, if the outer anchoring elements 310 a, 310 c are each coupledat one end to the central anchoring element 310 b, they may have adifferent diameter on each end. As the central anchoring element 310 bis stiffer, it may have a greater diameter than a less stiff element. Ingeneral, there is no limit to the number of anchoring elements that canbe provided or to the particular stiffness profile desired.

The securing force produced by the anchor can include a radial componentdirected outward and pressing against the walls of the surroundinglumen. The securing force can also include an axial component providedby a barb. The magnitude of the securing force preferably depends on theintended application being selected to sufficiently secure the anchorwithout being excessive. Limiting the maximum force is important assubstantial forces acting against the luminal walls are more apt totraumatize the surrounding tissue.

In some embodiments, the radially-outward force of an anchor is variedby varying the stiffness (or compliance) of the anchor along its length.Such a feature provides for greater flexibility in tailoring the anchorto its intended delivery location. For example, the thickness of theanchor member can be varied to control the desired stiffness, such thata portion of the anchor is relatively stiff, whereas another portion ofthe anchor is relatively soft. In this manner, the stiffer portion ofthe anchor can be used to distend that portion of the bodily lumenwithin which it is implanted. To reduce irritation, the stiffness isthen reduced towards the proximal and distal ends of the anchor toreduce any trauma to the tissue of the bodily lumen. For example, a sideview of a flexible intraluminal anchor 400′ is illustrated in FIG. 5A.By using different anchoring elements 410 a′, 410 b′, 410 c′,interconnected by joining members 420 a′, 420 b′ (generally 420′) asshown, the anchor 400′ is allowed to flex and bend. The joining members420′ are not necessary for embodiments in which the elements 410 areeach coupled to the same tube or sleeve. The anchoring elements 410′ areeach formed from a respective continuous wire fashioned into theoscillating, wave-shaped pattern shown. Viewed along an axis (notshown), the anchor 400′ would appear as an open circle or hoop.Wave-shaped anchors and related matters are described in U.S.application Ser. No. 10/858,852 filed on Jun. 1, 2004 and claimingpriority to U.S. Provisional Application Nos. 60/528,084 filed on Dec.9, 2003 and 60/544,527 filed on Dec. 13, 2004. The entire teachings ofthese applications are incorporated herein by reference in theirentirety.

In one embodiment, the central anchoring element 410 b′ is formed from arelatively thick wire, such as a 0.023 inch diameter Nitinol wire. Theadditional anchoring elements 410 a′, 410 c′ are formed from a thinnerwire, such as a 0.014 inch diameter Nitinol wire. Using wires formedfrom the same material, the thicker wire results in a greater stiffnessthan the thinner wire. Thus, the central anchoring 410 b ′elementprovides a greater radially-outward force when compressed than either ofthe two surrounding anchoring elements 410 a′, 410 c′. The spring ratecan also be varied by altering the axial length of a wave-shapedanchoring element, shorter elements being stiffer than longer ones.Also, the spring rate can be varied by altering the number ofoscillations for a give anchoring element, elements with moreoscillations being stiffer.

The wires can be formed from any suitable material, such as metals,metal alloys (e.g., stainless steel and Nitinol), and/or syntheticmaterials (e.g., plastic). Preferably, the material is bio-compatible,although it is possible to use non bio-compatible material that iscoated or encapsulated in a bio-compatible material. Anchoring can beaccomplished using an interference fit between the intraluminal anchorand the inner walls of the lumen. Alternatively or in addition,anchoring can be accomplished using other means including sutures,staples, surgical adhesives and/or barbs or hooks. In the exemplaryembodiment, at least one external barb 425′ is be attached to thecentral anchoring element 410 b′. When implanted, the barb 425′ is heldin place within muscular tissue by the stiffness and correspondingradially-outward force of the 0.023 inch diameter wire. The centralanchor element 410 b provides a substantial force to keep the barb 425′inserted into the surrounding tissue. Without the first and thirdanchoring elements 410 a′, 410 c′, the securing force provided by themiddle anchoring element 410 b′ could lead to tissue irritation or evendamage at the ends of the element 410 b′.

The anchoring elements described above can be formed into any number ofdifferent shapes. In some embodiments, each of the anchoring elements isformed in a wave shape. Thus, a linear element (i.e., a wire) iscontoured into an oscillating manner along a cylindrical surface at adistance (i.e., a radius) from a central axis. Such a wire form can beshaped on a cylindrical mandrel. The two ends of the wire are joinedtogether (e.g., crimped, soldered, or chemically or thermally bonded)forming a continuous structure. An anchoring element thus formedprovides a relatively small surface area in contact with the naturalbodily lumen, while allowing the anchor to provide a relatively largediameter (e.g., 25 to 50 or more millimeters for gastrointestinalapplications). The oscillations result in relatively straight segments412 a, 412 b (generally 412) interconnected at nodes 414 a, 414 b(generally 414). When compressed in a radial direction, the nodes 414flex allowing the relatively straight segments 412 to become morealigned with respect to each other. Thus, the diameter of the anchor400′ can be reduced substantially to allow for its insertion and/orremoval through a relatively small diameter. For example, in someintestinal applications, a 50-millimeter diameter device is adapted tobe inserted through a 12-millimeter diameter catheter. When released,the anchor 400′ expands with spring force against the walls of thebodily lumen.

The anchoring elements 410 a′, 410 b′, 410 c′ may be separated byrespective distances s₁, s₂ as shown, or one or more of the elements maybe adjacent or even overlapping. An alternative embodiment of awave-shaped wire anchor 400″ is illustrated in FIG. 5B. The anchoring400″ also includes multiple anchoring elements 410 a″, 410 b″, 410 c″that may or may not be interconnected by joining members 420 a″, 420 b″.As shown, one or more of the anchoring elements 410 a″, 410 b″, 410 c″can overlap another anchor element to varying degrees. At least oneadvantage of such an overlap is a reduction in the overall length of theanchor 400″. Such an overlap can also be used to achieve a desiredforce-versus-distance profile of the anchor 400″, leading to a moregradual transition of the forces distributed along the axis.

A side view of an alternative embodiment of an intraluminal anchor 500is illustrated in FIG. 6. The anchor 500 includes multiple anchoringelements 510 a, 510 b, 510 c, again shown as wave-shaped elements forillustrative purposes, that are interconnected to each other. Theanchoring elements 510 a, 510 b, 510 c can be interconnected bymechanical fasteners, chemical adhesives, thermal bonding, welding,soldering, and/or weaving. The interconnection may be fixed, or in thecase of a weave, capable of longitudinal compression.

As described above, the intraluminal anchor can be used to anchor anelongated tube within a natural bodily lumen. An exemplary device 600including an intraluminal anchor, similar to the one described above inreference to FIG. 5A, and coupled to the proximal end of an elongatedtube 615 is illustrated in FIG. 7. The tube 615 may be rigid, semi-rigidor flexible. Gastrointestinal sleeves and related matters are describedin U.S. application Ser. No. 10/339,786, filed Jan. 9, 2003, whichclaims the benefit of U.S. Provisional Application No. 60/430,321, filedDec. 2, 2002; and U.S. application Ser. No. 10/726,011, filed on Dec. 2,2003, which claims the benefit of U.S. Provisional Application No.60/512,145 filed Oct. 17, 2003. The entire teachings of all of theseapplications are incorporated herein by reference.

The anchoring elements 610 a, 610 b, 610 c (generally 610) can be bondedto the tube (e.g., chemically bonded using an adhesive, or thermallybonded). The anchoring elements 610 can also be mechanically coupled tothe elongated tube 615. For example, the anchoring elements 610 can becoupled using a suture, a surgical staple, and/or by threading theanchoring element itself through perforations in the elongated tube.

In some embodiments, the anchoring elements 610 are encapsulated withinthe elongated tube 615. For example, the elongated tube 615 can beformed as a sleeve. A portion the sleeve can then be used to encapsulatethe anchoring elements by folding one end of the sleeve back upon itselfto cover both the interior and exterior of the anchoring elements 610.The portions of the elongated tube forming the overlapping portion 617can then be coupled together, thereby capturing the anchoring elements610 and securing them in place with respect to each other and withrespect to the elongated tube 615. For example, the overlapping portionsof the tube 617 can be bonded together (e.g., chemically bonded using anadhesive, or thermally bonded). Alternatively or in addition, theoverlapping portions of the tube 617 can be mechanically fastenedtogether. For example, the overlapping portions of the elongated tube617 can be coupled together using sutures, staples, clasps, or any othersuitable mechanical fastener.

As shown, the anchor 600 can include barbs 620 that protrude externallyfrom the anchor 600 to penetrate the surrounding tissue. Forillustrative purposes, the device 600 as implanted within a portion ofan animal's intestine 630 illustrated in cross section. Shown are theintestinal wall 630 including an inner mucosal layer 632 incommunication with the anchor 600 and a surrounding layer of musculartissue 634. Preferably, the barbs 620 are adapted to penetrate themucosal layer 632 and into the muscular tissue 634 of the intestine 630.In some embodiments, the barbs 620 actually penetrate the outer walls ofthe intestine 630. Thus, the barbs 620 provide an axial securing forcecomponent, with the anchoring element 610 b providing a securing forceadapted to maintain the barbs into engagement with the muscular tissue634.

To ensure that the barbs 620 remain secured to the muscular tissueduring implantation, the anchoring element to which the barbs 620 arecoupled should be relatively stiff. Thus, the stiffness of thesupporting anchoring element 610 b maintains a radial force ensuringthat the barbs 620 are driven into the tissue. In some embodiments, thestiffness is sufficient to force the supporting anchoring element 610 bthrough the mucosal layer 632, abutting it to the layer of musculartissue 634.

In some applications, however, the stiffness of the anchoring element310 b can lead to irritation and possibly damage to the surroundingtissue. To reduce the possibility of such irritation or damage,additional anchoring elements 610 a, 610 c are provided on either sideof the anchoring element 610 b. Preferably, the additional anchoringelements 610 a, 610 c are less stiff (i.e., softer) than the centralanchoring element 610 b. In this manner, the transition betweenunanchored portions of the lumen and the stiff anchoring element 610 bis spread over a larger surface area to achieve the desired anchoringforce at the barbs 620 in a gradual manner. Thus, the additionalanchoring elements 610 a, 610 c provide a strain relief on both sides ofthe stiff anchoring element 610 b to minimize trauma to the tissue, asshown in FIG. 1B.

An exemplary embodiment of an intraluminal anchor anchoring an elongatedflexible sleeve within the intestine of an animal is illustrated in FIG.8. A lower portion of the stomach 700 is shown terminating in a pyloricsphincter 705. Distal to the sphincter 705 is the proximal duodenum 715,sometimes referred to as the duodenal bulb. The device of FIG. 7 isimplanted with the anchor being situated distal to the pyloric sphincter705, preferably within the duodenal bulb 715. The sleeve 600 can extendthrough the duodenum 710 and into the jejunum 720.

As described above in reference to wire anchoring elements, the radialforce, or stiffness can be controlled by varying a physical property ofthe anchoring element. This approach can also be extended beyond wireexamples. For example, the elongated anchoring element can be formedfrom a tapered tube. To vary the radial force, or stiffness, the tubecan be shaped to vary its wall thickness. The axial taper can beaccomplished by injection moulding to a desired shape and/or by removingmaterial from a solid elongated tube. The result in either case is ananchoring element having differing thicknesses along its central axis.FIG. 9A illustrates a cross-sectional view of an exemplary tube 800after having both ends tapered from a thicker middle section. Thus, thethinner ends 810 are achieved by removing extra material 820. Forexample, a stainless steel or alloy (e.g., Nitinol) tube 800 can beshaped by grinding it and/or turning it on a lathe to selectably removematerial along its length. As shown, the tube 800 can be tapered from arelatively thick portion along the tube middle, to a relatively thinportion at the tube's ends (with this approach, any conceivable profileis possible). The shaped tube 800, once tapered, can be furtherprocessed to form an expandable anchor. For example, referring to FIG.9B, apertures 920 can be cut into the shaped tube 900 walls using alaser. The remaining portions of the shaped tube 910, once cut, can forma continuous structure such as the interconnected network of struts 910shown, or even a wave structure as described above. Again, the resultingstructure provides an interior lumen 915, while also being radiallycompressible. A corresponding force-versus-distance profile for theexemplary tube 900 is illustrated in FIG. 9C.

As will be appreciated by those of skill in the art, there are manypotential variations to these methods and articles. Those variations areencompassed by this invention.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. An intraluminal implant comprising: an anchor configured to beimplanted within a natural bodily lumen, the anchor comprising aplurality of wave-shaped anchoring elements, at least one of theplurality of anchoring elements comprising at least one external barbconfigured to penetrate muscular tissue of the natural bodily lumen, therespective anchoring element expanding against the lumen and configuredto hold the barb against the muscular tissue; and a flexible, elongatedsleeve coupled at its proximal end to the anchor, the sleeve configuredto extend distally beyond the anchor within the natural bodily lumen. 2.The intraluminal implant of claim 1, wherein the anchor comprises two ofthe wave-shaped anchoring elements.
 3. The intraluminal implant of claim1, wherein the anchor comprises three of the wave-shaped anchoringelements.
 4. The intraluminal implant of claim 3, wherein at least oneexternal barb extends from a central anchoring element and the centralanchoring element is stiffer than two end anchoring elements.
 5. Theintraluminal implant of claim 1, wherein the sleeve is floppy.
 6. Theintraluminal implant of claim 1, wherein the external barb is abi-directional barb, comprising a first barb segment configured tooppose proximal movement and a second barb segment configured to opposedistal movement.
 7. The intraluminal implant of claim 1, wherein theelongated sleeve is configured to be anchored in the proximal duodenum,the sleeve extending distally within the intestine.
 8. The intraluminalimplant of claim 1, wherein the elongated sleeve is thin-walled,collapsing upon itself.
 9. The intraluminal implant of claim 1, whereinthe anchor is coupled to the sleeve between overlapping layers of thesleeve.
 10. The intraluminal implant of claim 1, wherein the anchor isradially collapsible for endoscopic insertion.
 11. The intraluminalimplant of claim 1, wherein the waves of the wave-shaped anchoringelements do not overlap axially.
 12. A method for anchoring a flexible,elongated sleeve within a natural bodily lumen, the method comprising:providing an anchor fixed to a proximal end of the flexible, elongatedsleeve, the sleeve extending distally into the natural bodily lumen, theanchor comprising a plurality of wave-shaped anchoring elements, atleast one of the plurality of anchoring elements comprising at least oneexternal barb; providing a radially-outward securing force from theanchor acting upon the natural bodily lumen; and piercing musculartissue of the natural bodily lumen with at least one external barb ofthe plurality of anchoring elements, the radially outward securing forcedriving the at least one barb into the muscular tissue.
 13. The methodof claim 12, further comprising inhibiting movement in either directionalong the natural bodily lumen using the at least one external barb. 14.The method of claim 12, further comprising at least partially radiallycollapsing the anchor for insertion of the anchor into the naturalbodily lumen.
 15. The method of claim 12, further comprising at leastpartially radially collapsing at least a portion of the anchor forremoval of the anchor from the natural bodily lumen.
 16. The method ofclaim 12, wherein the anchor comprises two of the wave-shaped anchoringelements.
 17. The method of claim 12, wherein the anchor comprises threeof the wave-shaped anchoring elements.
 18. The method of claim 17,wherein at least one external barb extends from a central anchoringelement and the central anchoring element is stiffer than two endanchoring elements.
 19. The method of claim 12, wherein the sleeve isfloppy.
 20. The method of claim 12, wherein the external barb is abi-directional barb, comprising a first barb segment configured tooppose proximal movement and a second barb segment configured to opposedistal movement.
 21. The method of claim 12, comprising anchoring thesleeve in the proximal duodenum and extending the sleeve distally withinthe intestine.
 22. The method of claim 12, wherein the sleeve isthin-walled, collapsing upon itself.
 23. The method of claim 12, whereinthe anchor is coupled to the sleeve between overlapping layers of thesleeve.
 24. The method of claim 12, wherein the waves of the wave-shapedanchoring elements do not overlap axially.